Mercedes Ortiz

Ablation of Electrograms With an Isolated, Delayed Component as Treatment of Unmappable Monomorphic Ventricular Tachycardias in Patients With Structural Heart Disease

OBJECTIVES We sought to evaluate the feasibility of identifying and ablating the substrate of unmappable ventricular tachycardia (VT). BACKGROUND Noninducible and nonstable VT cannot be ablated by the conventional approach. METHODS We studied 24 patients with documented monomorphic VT. Twenty-one patients had ischemic cardiomyopathy, two had nonischemic cardiomyopathy, and one had tetralogy of Fallot. Twelve patients had an implantable cardioverter-defibrillator. Conventional activation mapping was not possible in 18 patients: at least 1 of the clinical VTs or the clinical VT was not inducible in 12 patients, and VT was not tolerated in 6 patients. This group had experienced between 1 and 106 VT episodes in the month before the ablation procedure. Endocardial electroanatomic activation maps (Carto System) during sinus rhythm (SR) and right ventricular apex (RVA) pacing were obtained to define areas for which an electrogram displayed isolated, delayed components (E-IDC). These electrograms were characterized by double or multiple components separated by >/=50 ms. RESULTS One area of E-IDC was recorded in 20 patients, and 2 or more were recorded in 4 patients. In 23 patients, these areas were detected during RVA pacing; in only 14 during SR. An E-IDC area related to the clinical VT was identified in each patient. Ablation guided by E-IDC suppressed all but one clinical VT whose inducibility suppression was tested. During a follow-up period of 9 +/- 4 months, three patients had recurrences of the ablated VT and two of a different VT. CONCLUSIONS Electrograms with IDCs related to clinical VT can be identified in the majority of patients during RVA pacing. Radiofrequency ablation of E-IDC seems effective in controlling unmappable VT.

Tachycardia-Related Channel in the Scar Tissue in Patients With Sustained Monomorphic Ventricular Tachycardias Influence of the Voltage Scar Definition

Background—Endocardial mapping before sustained monomorphic ventricular tachycardia (SMVT) induction may reduce mapping time during tachycardia and facilitate the ablation of unmappable VT. Methods and Results—Left ventricular electroanatomic voltage maps obtained during right ventricular apex pacing in 26 patients with chronic myocardial infarction referred for VT ablation were analyzed to identify conducting channels (CCs) inside the scar tissue. A CC was defined by the presence of a corridor of consecutive electrograms differentiated by higher voltage amplitude than the surrounding area. The effect of different levels of voltage scar definition, from 0.5 to 0.1 mV, was analyzed. Twenty-three channels were identified in 20 patients. The majority of CCs were identified when the voltage scar definition was ≤0.2 mV. Electrograms with ≥2 components were recorded more frequently at the inner than at the entrance of CCs (100% versus 75%, P≤0.01). The activation time of the latest component was longer at the inner than at the entrance of CCs (200±40 versus 164±53 ms, P≤0.001). Pacing from these CCs gave rise to a long-stimulus QRS interval (110±49 ms). Radiofrequency lesion applied to CCs suppressed the inducibility in 88% of CC-related tachycardias. During a follow-up of 17±11 months, 23% of the patients experienced a VT recurrence. Conclusions—CCs represent areas of slow conduction that can be identified in 75% of patients with SMVT. A tiered decreasing-voltage definition of the scar is critical for CC identification.

Comparison of radiofrequency catheter ablation of drivers and circumferential pulmonary vein isolation in atrial fibrillation: a noninferiority randomized multicenter RADAR-AF trial.

BACKGROUND Empiric circumferential pulmonary vein isolation (CPVI) has become the therapy of choice for drug-refractory atrial fibrillation (AF). Although results are suboptimal, it is unknown whether mechanistically-based strategies targeting AF drivers are superior. OBJECTIVES This study sought to determine the efficacy and safety of localized high-frequency source ablation (HFSA) compared with CPVI in patients with drug-refractory AF. METHODS This prospective, multicenter, single-blinded study of 232 patients (age 53 ± 10 years, 186 males) randomized those with paroxysmal AF (n = 115) to CPVI or HFSA-only (noninferiority design) and those with persistent AF (n = 117) to CPVI or a combined ablation approach (CPVI + HFSA, superiority design). The primary endpoint was freedom from AF at 6 months post-first ablation procedure. Secondary endpoints included freedom from atrial tachyarrhythmias (AT) at 6 and 12 months, periprocedural complications, overall adverse events, and quality of life. RESULTS In paroxysmal AF, HFSA failed to achieve noninferiority at 6 months after a single procedure but, after redo procedures, was noninferior to CPVI at 12 months for freedom from AF and AF/AT. Serious adverse events were significantly reduced in the HFSA group versus CPVI patients (p = 0.02). In persistent AF, there were no significant differences between treatment groups for primary and secondary endpoints, but CPVI + HFSA trended toward more serious adverse events. CONCLUSIONS In paroxysmal AF, HFSA failed to achieve noninferiority at 6 months but was noninferior to CPVI at 1 year in achieving freedom of AF/AT and a lower incidence of severe adverse events. In persistent AF, CPVI + HFSA offered no incremental value. (Radiofrequency Ablation of Drivers of Atrial Fibrillation [RADAR-AF]; NCT00674401).

Usefulness of Unipolar Electrograms to Detect Isthmus Block After Radiofrequency Ablation of Typical Atrial Flutter

Background—RS morphology of the unipolar electrogram is associated with propagation of the wave front through the exploring electrode, whereas positive uniphasic (R) unipolar electrograms are characteristic of the end of activation. Methods and Results—Unipolar electrograms were recorded in 45 consecutive patients with atrial flutter who were undergoing radiofrequency ablation (RFA). Bidirectional cavotricuspid isthmus (CTI) block was achieved in 44 patients. The unipolar electrogram obtained before RFA at the low anterolateral right atrium during coronary sinus pacing changed from RS, rS, or QS to R or Rs in all patients after clockwise CTI block was obtained. The morphology of unipolar electrograms recorded close to the coronary sinus during pacing from the low anterolateral right atrium changed from RS or rS to R or Rs in all but 4 patients after counterclockwise CTI block. In the patient in whom CTI block was not achieved, the RS morphology of the unipolar electrogram remained unchanged. In 18 patients, the results of the RFA were assessed with only the unipolar electrogram. The unipolar electrogram correctly predicted 100% and 89% of the cases of clockwise and counterclockwise CTI block, respectively. Conclusions—The creation of CTI block is associated with an easily detectable loss of negative components and development of an R or Rs pattern of the unipolar electrogram recorded close to the ablation line while pacing at the opposite side of the CTI.

Randomized comparison of intravenous procainamide vs. intravenous amiodarone for the acute treatment of tolerated wide QRS tachycardia: the PROCAMIO study

Aims Intravenous procainamide and amiodarone are drugs of choice for well-tolerated ventricular tachycardia. However, the choice between them, even according to Guidelines, is unclear. We performed a multicentre randomized open-labelled study to determine the safety and efficacy of intravenous procainamide and amiodarone for the acute treatment of tolerated wide QRS complex (probably ventricular) tachycardia. Methods and results Patients were randomly assigned to receive intravenous procainamide (10 mg/kg/20 min) or amiodarone (5 mg/kg/20 min). The primary endpoint was the incidence of major predefined cardiac adverse events within 40 min after infusion initiation. Of 74 patients included, 62 could be analysed. The primary endpoint occurred in 3 of 33 (9%) procainamide and 12 of 29 (41%) amiodarone patients (odd ratio, OR = 0.1; 95% confidence interval, CI 0.03–0.6; P = 0.006). Tachycardia terminated within 40 min in 22 (67%) procainamide and 11 (38%) amiodarone patients (OR = 3.3; 95% CI 1.2–9.3; P = 0.026). In the following 24 h, adverse events occurred in 18% procainamide and 31% amiodarone patients (OR: 0.49; 95% CI: 0.15–1.61; P: 0.24). Among 49 patients with structural heart disease, the primary endpoint was less common in procainamide patients (3 [11%] vs. 10 [43%]; OR: 0.17; 95% CI: 0.04–0.73, P = 0.017). Conclusions This study compares for the first time in a randomized design intravenous procainamide and amiodarone for the treatment of the acute episode of sustained monomorphic well-tolerated (probably) ventricular tachycardia. Procainamide therapy was associated with less major cardiac adverse events and a higher proportion of tachycardia termination within 40 min.

Successful Catheter Cryoablation of Hisian Ectopy Using 2 New Diagnostic Criteria Based on Unipolar and Bipolar Recordings of the His Electrogram

Hisian Ectopy Cryoablation Using New Diagnostic Criteria. We describe the case of a 61‐year‐old woman who underwent successful catheter cryoablation of a symptomatic Hisian ectopy. Diagnosis was based on features of the HV interval assessed from a bipolar recording during mapping. The location of the arrhythmic focus was identified using simultaneous unipolar and bipolar recordings of the His electrogram. This case report highlights the use of 2 new criteria for the diagnosis and mapping of Hisian ectopy, and the successful use of cryothermia for the ablation of extrasystoles arising from the His bundle. (J Cardiovasc Electrophysiol, Vol. 23 p. 325‐329, March 2012.)

Spectral analysis of intracardiac electrograms during induced and spontaneous ventricular fibrillation in humans

AIMS Very limited data are available on the differences between spontaneous and induced episodes of ventricular fibrillation (VF) in humans. The aim of the study was to compare the spectral characteristics of the electrical signal recorded by an implantable cardioverter defibrillator (ICD) during both types of episodes. METHODS AND RESULTS Thirteen ICD patients with at least one spontaneous and one induced VF recorded by the device were included in the study. A spectral representation was obtained for the first 3 s of the intracardiac unipolar electrogram during VF. The dominant frequency (f(d)), the peak power at f(d), an organization index (OI), a bandwidth measurement, and an estimate of the correlation with a sinusoidal wave (leakage) were estimated for each episode. The f(d) was higher in induced episodes (4.75 +/- 0.57 vs. 3.95 +/- 0.59 Hz for the spontaneous episodes, P = 0.002), as well as the degree of organization assessed by the OI, bandwidth, and leakage parameters. CONCLUSION Clinical and induced VF episodes in humans have different spectral characteristics. Changes in the electrophysiological substrate or in the location of the arrhythmia wavefront at onset could play a role to explain the observed differences.

Ablación de taquicardia ventricular mediante radiofrecuencia en pacientes con cardiopatía isquémica

Objetivo. Analizar la eficacia de la ablacion mediante radiofrecuencia en pacientes con cardiopatia isquemica y taquicardia ventricular, asi como el significado clinico de la inducibilidad de taquicardia ventricular previamente no documentada (taquicardias ventriculares no clinicas). Metodos. Se trato con radiofrecuencia a 34 pacientes (61 ± 10 anos; fraccion de eyeccion ventricular izquierda 31 ± 10%) con cardiopatia isque-mica y taquicardia ventricular clinicamente documentadas. Se aplico radiofrecuencia en 34 taquicardias ventriculares clinicas y 11 taquicardias ventriculares no clinicas. Se considero exito terapeutico inicial cuando ninguna de las taquicardias ventriculares tratadas con radiofrecuencia fueron reproducibles en el estudio previo al alta hospitalaria. Resultados. En 23 pacientes (68%) se realizo ablacion con exito de la taquicardia ventricular clinica. Se consiguio el exito terapeutico inicial en 21 pacientes (62%). En 6 de los 21 pacientes se indujeron 7 taquicardias ventriculares no clinicas mal toleradas y no recibieron tratamiento adicional. Durante un seguimiento de 26 ± 15 meses, 6 (29%) de los 21 pacientes con exito terapeutico inicial presentaron taquicardia ventricular espontanea. Cinco de los 6 pacientes que recurrieron estaban entre aquellos dados de alta sin ninguna taquicardia ventricular inducible. Tres pacientes fallecieron durante el seguimiento: dos de causa cardiaca no arritmica, uno de ellos con recurrencia previa y el paciente restante subitamente, sin recurrencias previas, con asistolia como primer ritmo documentado tras la perdida de conciencia. Conclusiones. En nuestra serie de pacientes con taquicardia ventricular y cardiopatia isquemica seleccionados para ablacion, la tasa de exito terapeutico inicial es del 62% y a medio plazo del 44%. Aunque la probabilidad de recurrencia de taquicardia ventricular es significativa (29%), esta no pare-ce relacionada con la inducibilidad de taquicardias ventriculares no clinicas.

Incidence, determinants, and prognostic implications of true pleomorphism of ventricular tachycardia in patients with implantable cardioverter-defribillators: a substudy of the DATAS trial

Background—The occurrence of monomorphic ventricular tachycardia (M-VT) with >1 QRS morphology during the same episode (pleomorphism [PL]) or in different episodes (multiple morphologies [MM]) has been described through ECG. Implantable cardioverter-defribillator (ICD) electrograms (EGs) provide the opportunity to analyze virtually all spontaneous M-VT episodes. We sought to study the incidence, determinants, and prognostic significance of PL and MM as assessed by ICD-EG in a prospective series of patients with ICDs. Methods and Results—Spontaneous episodes of M-VT were analyzed before ICD intervention. PL was defined as >1 ICD-EG morphology, each having ≥6 consecutive identical beats during the same VT episode, and MM as >1 ICD-EG morphology in different M-VT episodes in the same patient. We analyzed 1881 M-VT episodes from 315 patients followed for 17 months. PL and MM occurred in 6% and 19%, respectively, of the total population (16% and 62% of patients with M-VT). Recurrent M-VT as diagnosis for ICD indication predicted PL and MM. Patients with PL more frequently developed MM (85% versus 15%; P<0.001) compared to patients without PL. Total mortality (5%) was significantly higher in patients with PL (20%), in patients with MM (11.5%), and in women (12%). In multivariate analysis, only PL (odds ratio, 5.33; P=0.009) and female sex (odds ratio, 3.1; P=0.038) predicted mortality. Conclusions—In a prospective series of patients with ICDs, mostly indicated for secondary prevention, both PL and MM of VT, as judged by ICD-EG, were not uncommon and were strongly associated. Female sex and the development of PL VT were the only independent predictors of mortality.

Determinants of inducibility of ventricular tachycardia.

We analyzed the incidence and predictive factors for induction of clinical ventricular tachycardia (VT) during an electrophysiologic study in 127 patients with structural heart disease and spontaneous VT documented by 12-lead electrocardiography. Eighty-five patients had coronary artery disease (CAD), 24 had idiopathic dilated cardiomyopathy (IDC), and 18 had right ventricular dysplasia (RVD). Clinical variables were age, gender, electrocardiographic patterns of spontaneous arrhythmia, cardiac diagnosis, left ventricular (LV) ejection fraction (EF), infarct location, and presence of LV aneurysm. Clinical VT was induced in 76 patients (60%, group 1) and was not induced in 51 patients (group 2). Clinical VT was induced in 83% of patients with RVD, 58% of patients with CAD, and 50% of patients with IDC (p = 0.07). LVEF tended to be significantly higher in group 1 than in group 2 (p = 0.06). The presence of left QRS axis in the frontal plane during spontaneous VT was significantly associated with a higher inducibility both in the general group (69% vs 46%, p <0.02) and in patients with CAD (70% vs 44%, p <0.02). In patients with CAD, only the presence of a left QRS axis was significantly associated with a higher inducibility. A multivariate analysis identified only the left QRS axis as a significant and independent predictor of induction of clinical VT. The association of a leftward axis with inducibility suggests that vectorial factors in the depolarization wavefronts may be related to inducibility since conventional stimulation is performed from the right ventricle, producing a leftward axis in most cases.